Once a structure has been deformed, it's never as strong as it was before. It's like how an aircraft structure is designed for a certain load limit with a 50% safety margin. So, if the plane is certified under aerobatic rules, it can repeatedly pull 6Gs (minimum) without deformation. However, the structure begins to deform as soon as you pull more than 6Gs but can't fail until it reaches the 50% margin of 9Gs. However, if you've exceeded the design limit, the failure limit will be lower on subsequent flights. In the case of this tank, it may not be strong enough to fly anymore.

SpaceX will have to examine the tank to see if there is permanent damage. I don't know if there's a practical way to replace the tank. Given how rocket structures are often designed, this may not be feasible.